An optimal correspondence of temporal information between the physical world and our perceptual world is an important factor for survival. It is generally agreed that the perceived temporal order of events is linked to our concept of causality: by Nature's law, the cause precedes the effect in time. Does the same temporal order necessarily hold in our perceptual awareness? Previous studies have revealed specific discrepancies between physical time and time perception. However, the relationship between the perceived time of events and the dynamic state of their neuronal representations remains largely unexplored. In the current psychophysical study, we demonstrate a striking phenomenon in which the cause of a perceptual event is perceived after the event itself. We used a paradigm referred to as motion-induced blindness (MIB) in which a static visual stimulus presented on a constantly rotating background disappears and reappears from awareness periodically, with the dynamic characteristics of bistable perception. A sudden stimulus onset (e.g., a flash) presented during a period of perceptual suppression (i.e., during MIB) is known to trigger the almost instantaneous reappearance of the suppressed stimulus. Surprisingly however, we report here that although the sudden flash is the cause of the reappearance of the static target (the corresponding effect), it is systematically perceived as occurring after this reappearance. In other words, the distinct neural signatures of conscious and unconscious events in the brain result in a perceived temporal order that contradicts the causal relation between the two events. This illusion thus sheds important light on the neural mechanisms of time perception and visual awareness.

This research was supported by post-doctoral funding from the CNRS and the French Ministry of Research to C-T. W. by grants from the ANR (project ANR 06JCJC-0154), the Fyssen Foundation and the EURYI to R.V. and by the.